Lubricating oil additive concentrates



y 1966' w. K. DETWEILER ETAL 3,249,539

LUBRICATING OIL ADDITIVE CONCENTRATES Filed July 50, 1962 PRECIPITATION OF CRYSTALLINE ANTIOXIDANT OF SEEDED ADDITIVE CONCENTRATES I400 HOURS STORAGE AT 40F \KJWITHOUT POUR DEPRESSANT WITH POUR DEPRESSANT VOLUME BASE OIL inventors Patent Attorney 3,249,539 LUBRICATING OIL ADDITIVE CONCENTRATES William K. Detweiler, Westfield, and Robert C. Gregor,

Roselle Park, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed July 30, 1962, Ser. No. 213,298 3 Claims. (Cl. 25233.4)

This invention relates to lubricating oil additive concentrates and to their methods of preparation. Particularly, the invention relates to improved lubricating oil additive concentrates containing crystalline antioxidants, which concentrates exhibit improved storage stability. -More particularly, the invention relates to methods of inhibiting crystallization and sedimentation of crystalline antioxidants contained in lubricating oil additive concentrates.

Lubricating oil additives are customarily supplied in the form of oil concentrates which can be ultimately diluted with additional base oil to form final lubricating compositions. Such concentrates are advantageous since they may be economically stored and transported. It is obvious, therefore, that the lowest possible volume of concentrate is to be desired. A limiting factor, however, is the solubility of the particular additives contained in the concentrates. Particularly, the storage stability of additive concentrates containing various crystalline antioxidant materials is often extremely poor because of the tendency of such materials to crystallize and to form a heavy sediment upon extended storage. The resulting sedimentation presents the ultimate user of the additive concentrates with handling and dilution problems. One solution to these problems has been the addition of larger volumes of base oil to the concentrates, which, of course, partially defeats the intended purpose of the concentrates, namely, storage and handling facility.

The present invention is concerned with the inhibition of the above-mentioned crystallization and sedimentation of crystalline antioxidant materials which are customarily contained in various lubricating oil additive concentrates. Accordingly, it has been surprisingly discovered that such crystallization and sedimentation of crystalline antioxidants can be inhibited by the addition of various materials which are well known in the art as pour point depressants. It is realized, of course, that pour point depressants are conventionally included in lubricating compositions. The present invention is concerned with the discovery that the addition of such pour point depressants to compositions containing relatively high concentrations of crystalline antioxidant materials will effectively inhibit their crystallization and settling (i.e. sedimentation) properties. While the exact mechanism of suchinhibition is not known, it is believed that the pour point depressant alters the crystallization characteristics of the antioxidant material such that the rate of crystal formation (i.e. nucleation) tends to predominate over the rate of crystal growth. Consequently, the formation of microcrystals is favored, as opposed to the formation of larger crystals which would have a tendency towards further growth and consequent settling. It is to be understood, however, that it is not intended to limit the present invention to the above theory.

In general, the present invention is applicable to lubricating oil additive concentrates containing crystalline antioxidant materials, which antioxidant materials have a tendency towards crystallization and sedimentation. Examples of various well-known classes of antioxidants contemplated are the following: aromatic amines, such as the naphthylamines, e.g. phenyl-alpha-naphthylamine, phenyl-beta-naphthlyamine, etc.; diphenylamines, e.g. p,p'- dioctyl diphenylamine, p-mono-octyl diphenylamine, pamino diphenylamine, etc.; phenols, e.g. ditertiary butyl A United States Patent 3,249,539 Patented May 3, 1966 p-cresol, di-tertiary butyl phenol, di-tertiary-butyl-alphamethoxy p-cresol, etc.; bis phenols, e.g. 4,4'-methylene bis(2,6-ditertiary butyl phenol), p,p'-isopropylidine diphenol, 4,4'-methylene bis(6-tertiary-butyl-o-cresol), 4,4'- bis(2-methyl-6-tertiary-butylphenol), 4,4'-bis(2,6-di-tertiary-butylphenol), etc. and aminophenols, e.g. di-tertiarybutyl-alpha-dimethylamino-p-cresol.

The pour point depressants suitable for use in the present invention include the various well-known materials which are capable of depressing the pour point of mineral oils. Thus, by pour point depressant is meant a material capable of lowering the limiting temperature at which a mineral oil maintains its free flowing characteristics.

Among the pour point depressants contemplated are the condensation products of paraflin wax, e.g. chlorinated paraffin wax; and aromatic compounds, e.g. naphthalene, anthracene, phenol, etc.; polymers of acrylate and methacrylate esters; acylated and/or alkylated vinyl aromatic polymers, e.g. alkylated polystyrene, etc. Also to be mentioned are the various copolymeric materials which exhibit pour depressant properties such as the copolymers of vinyl esters, e.g. vinyl acetate, and dicarboxyic acid esters, e.g. alkyl fumarates; as well as the terpolymers formed by incorporating a butyrolactam or a dicarboxylic acid anhydride into the latter copolymer. Ex-

amples of typical terpolymers would include the terpolymers of alkyl fumarate-vinyl acetate-maleic anhydride, alkyl fumarate-vinyl acetate-N-vinyl pyrollidone, etc.

In general, the concentrates of the present invention will comprise a major proportion of a mineral base oil, a minor amount of a crystalline antioxidant material and a minor-amount of a pour point depressant sufficient to inhibit crystallization of the antioxidant material. Generally, about 0.005 to 2.0 wt. percent of the pour point depressant will inhibit crystallization of about 1.0 to 10.0 wt. percent of the antioxidant material, said weight percents being based on the total weight of concentrates.

Various other Well-known lubricating additives may also be incorporated into the above concentrates, such as other antioxidant materials, antiwear agents, corrosion inhibitors, detergents, detergent-inhibitors, antifoamants, etc.

' One typical concentrate which may be effectively inhibited against the crystallization of crystalline antioxidant materials by the incorporation of a pour point depressant is the concentrate of the lubricating composition disclosed in U.S. Patent 3,007,869. This patent discloses a lubricating composition comprising a mineral lubricating oil base and minor amounts of an alkaline earth metal sulfonate detergent, e.g. calcium or barium sulfonate; an alkaline earth metal salt of an alkyl phenol sulfide, e.g. calcium-barium nonyl phenyl sulfide; and phenyl-alphanaphthylamine as the crystalline antioxidant material. As disclosed in that patent, the lubricating oil base is a hydrofined and phenol-extracted coastal distillate, boiling between 340 and 700 F. at 10 mm. Hg pressure, having a viscosity index in the range of 50 to and a viscosity at F. in the range of 800 to 1200 SSU. The alkaline earth metal sulfonates contemplated are either the alkaline earth metal salt of petroleum sulfonates or the calcium or barium synthetic sulfonates well known in the art. Preferably, the sulfonic acid portion ofthe metal salt has a molecular weight in the range of about 300 to 1000. The calcium sulfonate contains 2 to 5 wt. percent calcium and the barium sulfonate 10 to 20 wt. percent barium. The alkaline earth metal salts of alkyl phenol sulfide disclosed in that patent are described in numerous other U.S. patents, as for example U.S. Patents 2,362,289, 2,461,335, and 2,480,664. Of these metal salts the mixed alkaline earth metal salts are preferably utilized. Such cent active ingredient.

from the labove descrribed additive solutions.

concentrate to one part base .oil.

3 salts may be prepared by neutralizing a phenol sulfide with a mixture of basic compounds of the alkaline earth metals, e.g. the hydroxides, or may be prepared by first partially neutralizing the phenol sulfide with one of the metals and then completing the neutralization by treatment with a suitable basic compound of the other metal. The alkyl phenol sulfide preferably has an alkyl side chain of 5 to 25 carbon atoms attached to each benzene nucleus. The mixed metal portion of the salt will normally consist of to 85 wt. percent of calcium and 85 to 15% of an alkaline earth metal, e.g. barium.

Concentrates of the above compositions will generally comprise a major portion of mineral oil; about 5 to 30 wt. percent, preferably 10 to wt. percent, of the alkaline earth metal sulfonate; about 5 to 20 wt. percent, preferably 5 to 10 wt. percent of the alkaline earth metal phenate sulfide; and about 1.0 to 10 wt. percent preferably 1.0 to 5.0 wt. percent of phenyl-alpha-naphthylamine.

Usually, the alkaline earth metal phenate sulfide and the alkaline earth metal sulfonate are supplied in the form of mineral oil solutions containing about 40 to 50 wt. per- The mineral oil utilized in such solutions usually has a viscosity of about 100 SSU at 100 F. The concentrates will, therefore, usually contain two different mineral oils; namely, the oil just described and the base oil used in the final lubricating compositions. Genena'lly, the base oil will be present in the conwnt-rates in an amount within the range of 35 to 55 wt. percent, preferably 40 to 50 wt. percent. The remainder of the mineral oil present in the concentrates will be derived As indicarted, however, the total amount of mineral oil in the concentrates will generally be greater than 50 wt. percent.

According to the present invention, a sufficicnt amount of pour point depressant material which will effectively inhibit crystallization of the phenyl-alpha-naphthylamine will generally be within the range of about 0.005 to 2.0 Wt.'percent preferably 0.01 to 0.5 wt. percent. A preferred class of pourpoint depressants comprises the condensation products of chlorinated paraflin Wax and aromatic compounds, e.g. chlorinated paraffin wax-naphthalene. Typical methods of producing a chlorinated paraffin wax-naphthalene product are disclosed in U.S. Patent 2,297,292 and 2,174,246.

The additive concentrates of the present invention are added to the base oil in a weight ratio of about one part This ratio may, of course, be readily varied depending on the desired final lubricating oil composition.

The invention will be further understood by reference to the following examples, which are given for illustrative purposes only andare not intended to limit the invention.

EXAMPLE 1 10 mm. Hg pressure) having a viscosity index of 63 and a viscosity at 100 F. of 1029 SUS. A calcium-barium mixed salt of nonyl phenol sulfide (42.0 wt. percent active ingredient in oil) and calcium sulfonate (44.5 Wt. percent active ingredient in oil) were then added to the base oil followed by the addition of phenyl-alpha-naphthylamine. The calcium-barium nonyl phenol sulfide oil solution contained 3.5 4 wt. percent sulfur, 2.35 wt. percent barium and 1.99 Wt. percent calcium, with the nonyl group being derived from tripropylene. The calcium sulfonate was a synthetic sulfonate and had an average molecular weight of about .900. Additionally, 0.008 wt. percent of an antifoarnant (Dow Corning 200, a dimethyl silicone of 350 cs. viscosity) was added .to each concentrate.

Table I CONCENTRATE COMPOSITIONS 1 Hydrofined and phenol-extracted coastal distillate: V.I. 63; viscosity F., 1030 Sue.

2 Paranox 43, supplied by Enjay Chemical active ingredient in mineral oil of 100 SSU 100 3 Paranox 24, supplied by Enjay Chemical 00.; 44.5 wt. percent active ingredient in mineral oil of 100 SSU 100 F.

4 Dow Corning 200-a dimethyl silicone of 350 cs. viscosity.

Another series of concentrateswas prepared identically to those listed in Table I except that 0.08 wt. percent, based on the total weight of the final concentrate of a 50% active ingredient oil solution of a chlorinated paraffin wax-naphthalene condensation product was added to eachconcentrate. This material is a well-known pour point depressant, supplied under the trade name Paraflow 149 by Enjay Chemical Co.

Samples of the abovetwo series of concentrates (i.e. with and without the pour point depressant( were stored %o.; 42.0 wt. percent in glass bottles for a period of 1400 hours at 40 F. Just prior to storage, each concentrate sample was seeded with a minute granule of undissolved phenyl-alpha-naphthylamine in order to facilitate crystallization. After storage, the concentrates were examined for crystallization and sedimentation of the phenyl-alpha-naphthylamine. Each concentrate was given a precipitate demerit based on a scale of 0 to 10, with 0 representing absence of crystallized sediment, and 10 representing very heavy sediment. The demerits were determined by measuring the precipitate height in each sample bottle. The sample having the greatest precipitate heightwas arbitrarily given a precipitate demerit of 10. The demerits of the other samples were determined by dividing the precipitate height of each lsample by the greatest precipitate height and multiplying The results are summarized in Table II and illustrated graphically in the accompanying drawing.

Table II Precipitate Demerit Concentrate Number With Pour Depressants Without Pour Depressant Her-.000

As shown in the above table and accompanying drawing, the incorporation of a pour point depressant into a lubricating oil additive concentrate containing a crystalline antioxidant effectively inhibits the crystallization of the antioxidant upon extended periods of storage. Furthermore, it is apparent that such inhibitionis eifective over a wide concentration range. As shown in the drawing, the curve of precipitate demerit vs. volume percent base oil'for those-concentrates containing the pour depressant is consistently lower than the curve for the same concentrates without the pour depressant. It is 3 apparent, therefore, that the present invention enables the formation of additive concentrates of improved storage stability.

' EXAMPLE 2 As a further example of the invention, a lubricating oil additive concentrate having the composition of Concentrate Number 1 (Table I), and additionally containing 0.08 wt. percent (based on the total Weight of the final concentrate) of achlorinated parafiin wax-naphthalene condensation product, is added to an equal Weight of the base oil defined in Example 1, in order to impart improved oxidation stability to said oil.

In sum, the present invention relates to improved additive concentrates containing crystalline antioxidant material and to their methods of preparation, which methods involve the addition of pour point depressants to said concentrates in order to inhibit crystallization of crystalline antioxidants therefrom.

What is claimed is:

1. An improved lubricating oil additive concentrate comprising a major, amount of mineral lubricating oil, about 5 to 30 Wt. percent of an alkaline earth metal sulfonate, about 5 to 20 Wt. percent of an alkaline earth metal phenate sulfide, and about 1 to 10 wt. percent of an antioxidant having a tendency towards crystallization and sedimentation from said concentrate, said antioxidant Paraflow 149 pour depressant.

0 being selected from the group consisting of aromatic amines, and phenols, and about 0.005 to 2 wt. percent of a chlorinated paraflin Wax-naphthalene condensation product suflicient to inhibit the said crystallization and sedimentation of said antioxidant.

2. An improved lubricating oil additive concentrate as defined in claim 1 wherein said antioxidant is phenylalpha-naphthylamine.

3. An improved lubricating oil additive concentrate as defined in claim '1 wherein said sulfonate is calcium sulfonate, said phenate sulfide is calcium-barium nonylphenate sulfide, and said antioxidant is phenyl-alph-anaphthylamine.

References Cited by the Examiner UNITED STATES PATENTS 2,174,246 9/1939 Lieber et al 25259 X 2,297,292 9/1942 Davis et a1 252-59 2,976,240 3/ 1961 Gilbert et al 25250 X 3,007,869 11/1961 Nunn 252-33.4'

OTHER REFERENCES Georgi: Motor Oils and Engine Lubrication, Reinhold Pub. Corp., 1950, pp. 188-195 pertinent.

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. AN IMPROVED LUBRICATING OIL ADDITIVE CONCENTRATE COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL, ABOUT 5 TO 30 WT. PERCENT OF AN ALKALINE EARTH METAL SULFONATE, ABOUT 5 TO 20 WT. PERCENT OF AN ALKALINE EARTH METAL PHENATE SULFIDE, AND ABOUT 1 TO 10 WT. PERCENT OF AN ANTIOXIDANT HAVING A TENDENCY TOWARDS CRYSTALLIZATION AND SEDIMENTATION FROM SAID CONCENTRATE, SAID ANTIOXIDANT AMINES, AND PHENOLS, AND ABOUT 0.005 TO 2 WT. PERCENT OF A CHLORINATED PARAFFIN WAX-NAPHTHALENE CONDENSATION PRODUCT SUFFICIENT TO INHIBIT THE SAID CRYSTALLIZATION AND SEDIMENTATION OF SAID ANTIOXIDANT. 